1. Technical Field
The present disclosure relates to optical field and, particularly, to a lens and an illumination device having the lens.
2. Description of Related Art
At present, the light emitted from many types of light sources, such as light emitting diodes, discharge lamps, halogen lamps, etc., has a large divergence angle. When one of these types of light sources is provided for illumination, a focus lens is generally required at the front of it to reduce the divergence angle. Typically, the focus lens makes the illumination area of the light source round; however, in some products, such as road lamps, tunnel lamps, etc., the illumination area of the light source should be rectangular to improve the efficiency of the light utilization of the light source.
What is needed is a lens which can ameliorate the problem of the prior art.